Qemu 5.1.0-1 GPU passthrough - MacOS vm starts only if hdmi is attached

[Daniele]

Hi,
I have a macOS 10.15.7 vm with GPU passthrough (NVIDIA GTX Titan Black), libvirt xml has path to vbios too.
Qemu 5.1.0-1 with libvirt 6.5.0-2 are installed in manjaro architect 20.1.1 (two kernels tried: 5.4.67 LTS and 5.8.11 stable, no difference).
I have two monitors, one with hdmi and one with vga inputs.
Usually the gpu is connected to one monitor with hdmi, the other one with DVI (on gpu)-->vga adapter, so:
1st monitor: hdmi-->hdmi
2nd monitor: DVI-->vga adapter-->vga

With this setup, launching "virsh start Catalina" has no problem.

If I detach the hdmi cable from monitor 1, I cannot start qemu anymore: the 2nd monitor turns black, it doesn't seem it has "no-signal", but only a black screen with the power led blinking (usually a window on the monitor floats around with "no signal" displayed when there is no signal to monitor).
I say "qemu doesn't start" because in /var/log/libvirt/qemu/Catalina.log there's no trace.

Detaching hdmi works with qemu 4.2 and libvirt 5.10, so this could be related to qemu update.

Apologize, I know there aren't much information here, if someone can guide me to test the issue I would be grateful.

Thanks for your attention

[Daniele (ghost82)]

Sorry, this is invalid, not related to qemu, the root of the issue is with OVMF_CODE.fd and OVMF_VARS.fd from v. 202005 or v. 202008 stable.